As a result of recent developments in medical techniques and in the general medical care of hearts, a number of serious and mild cardiac diseases have been discovered and aided by cardiac therapy. However, mild cardiac patients, particularly mild cardiac sick children discovered at school by cardiac examinations conducted nationwide, have been prevented from swimming as being too severe an exercise.
In conventional infant circulatory organ science, the reason that the mild cardiac infant cannot swim safely is the result of consideration of the energy consumption and the result of inspection of an electrocardiogram of the infants on the ground. So far, there has been no electrode for recording the electrocardiogram during swimming. Therefore, the swimming restrictions are not based on results of the inspection of an electrocardiogram recorded during actual swimming.
However, the circulatory action during swimming is different from that during exercises on the ground, and abnormal variations are observed during swimming. On the other hand, at present, since accurate circulatory action of a pupil during swimming is unknown, the safety of the mild cardiac sick pupil during swimming cannot be confirmed. It is difficult to give approval for swimming to the mild cardiac sick pupil based on a conventional inspection. Consequently, it becomes necessary to prove that the pupil can swim safely by recording an electrocardiogram during actual swimming.
In order to record the electrocardiogram of the living body during swimming, it is necessary to detect ultrafine currents induced on the skin of the living body during swimming by electrodes bonded on the skin, to lead it to an electrocardiograph on the ground and to measure the variation in the potential generated in a living body by the electrocardiograph.
Since the electrodes bonded on the skin of the living body are easily separated from the skin in the water, the electrodes may be bonded with adhesive or bonding agent on the skin in some cases. However, it is troublesome to bond the electrodes on the skin and it gives a load for an examinee. Even if the electrodes are bonded with adhesive on the skin, they can be separated from the skin during severe swimming exercise. Further, since the waterproofness of the electrodes may not be adequate, there is a drawback that a good electrocardiogram of the living body during swimming cannot be obtained.
In order to record the electrocardiogram of the living body during swimming, it is necessary to put the electrode on the skin surface of the living body and to connect each of the electrodes through respective cables to an electrocardiograph placed on the ground.
In case that the electrocardiogram of the living body during swimming is recorded by the electrocardiograph placed on the ground as described above, when the living body swims for a long distance, the cable must be lengthened in response to the swimming distance. As the cable becomes longer, the cost increases, and it arises that an accurate electrocardiogram cannot be obtained due to leakage phenomenon of the ultrafine current.